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Re^2: The energy shifts in XMCQDPT calculation.


On Thu Aug 16 '12 2:13pm, sanya wrote
>The problems in QDPT frequently arise from errors or problems in CASSCF. From your outputs, I see that root flipping occurs: in 136CASSCF-10-10PT34 State 1 was closed-shell (all occupancies are close to 2 and 0), while in 135CASSCF-10-10PT34 I see fractional occupancies of orbital 5 (1.43) and 6 (0.57). Can you show us your CASSCF inputs and outputs?
>In addition, you'd better set $XMCQDPT group as follows:

>! (instead of kstate(1))
>  nstate=34
>! (additional parameters: you need 3 states, so 3 1's)
> wstate(1)=1,1,1,-0 avecoe(1)=1,1,1,-0
>  edshft=0.02
> $end

>I think this improvement alone will not help you, unless you find out what is wrong with your CASSCF.

Thank you for your reply.

I attached the CASSCF inputs and outputs with this post. It seems the MOs in active space remain intact, while the CI roots differ at points of interest. So that can be the cause of the jump. However, the root flipping, you've mentioned, is due to the physics of the problem. So It will be great if the energy profile could be kept smooth, while root flipping is present.

Thanks for your help,

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[ ] CASSCF inputs and outputs

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